, kevin collin's mother. as you see in these exclusive pictures three invest investigators from the san francisco police department isn't several hours tonight talking to kevin collin's mother, two of his sisters and a brother. we know police showed them this picture of the lead suspect dan therrien who died in 1978. they also showed them what he looked like in 1974, when witnesses say they saw kevin talking to a man with a big black dog. >> i am convinced that the investigation is going in the right direction. >> reporter: that direction led them last week to dig up the concrete floor of the garage of this house on masonic where therrien lived. two different cadaver dogs alerted at the same spot. they believe the dog fragments found may be dog not human. two witnesses who saw kevin with a man with a dog back then could not pick thierrien out of a photo line up. >> that's correct neither of them could. >> reporter: now less than two hours ago anne collins left here with her daughters. saying police told them